This invention relates to a back-mirror for a vehicle, which is adapted to be mounted on the outside of the vehicle and connected to an operable means provided within the vehicle for controlling an angular movement of the back-mirror to provide a convenient view to a driver of the vehicle, and, more particularly, to an electric remote control back-mirror assembly for adjusting the angular movement of the back-mirror on the vehicle to the right position without causing the unstable state or deterioration among mechanisms for the movement of the back-mirror.
Since the backmirror is located out of the reach of the driver of the vehicle in the line of vision to permit the driver to observe traffic conditions behind the vehicle without shifting the driver's eyes too far out of the line of travel of the vehicle, it is necessary to provide mechanisms for moving the back-mirror to the desired positions on the vehicle through a remote controlled operation of the driver from the inside of the vehicle and, preferably, including a back-mirror assembly for adjusting the angular movement of the back-mirror into more precise positions.
Conventionally, such a construction of this type of back-mirror assembly has been known that two connecting parts which are crossed at right angles to an inclination center at the back face of a back-mirror are respectively connected with the heads of screw rods and, by pushing and pulling the screw rods to be driven by a motor, the back-mirror is inclined, as described within U.S. Pat. No. 3,609,014, patented on Sept. 28, 1971. However, in the case of the back-mirror assembly having the construction as described above, the two connecting parts move to draw a parenthesis shape with respect to the inclination center, while the screw rod moves a straight line, and consequently, the motor may be sometimes caused to be locked by an unnecessary force delivered when the back-mirror is inclined so much. In order to prevent this, it has been proposed that the screw rod is made of an elastic material such as polyurethane rubber so that the unnecessary force may be reduced owing to the transformation of the elastic screw rod, and the engagement of a driving gear into the screw rod is made use of also as a clutch. However, it cannot be prevented by the arrangement as has been proposed that the motor is loaded too much around the position where the back-mirror is inclined by the maximum angles, and moreover there has been such a problem that the elastic screw rod becomes hard when it is cold, thus losing the effectiveness thereof as an elastic body.